JP2014136640A - Sheet feeder and image forming apparatus - Google Patents

Sheet feeder and image forming apparatus Download PDF

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JP2014136640A
JP2014136640A JP2013007208A JP2013007208A JP2014136640A JP 2014136640 A JP2014136640 A JP 2014136640A JP 2013007208 A JP2013007208 A JP 2013007208A JP 2013007208 A JP2013007208 A JP 2013007208A JP 2014136640 A JP2014136640 A JP 2014136640A
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sheet
dc motor
feeding
remaining amount
sheets
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JP2013007208A
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JP2014136640A5 (en
JP6029476B2 (en
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Shunsuke Okazaki
俊介 岡崎
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Canon Inc
キヤノン株式会社
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Abstract

PROBLEM TO BE SOLVED: To provide a sheet feeder and an image forming apparatus comprising configurations advantageous in terms of cost and installation space by reducing as much as possible dedicated configurations to be specially added for determination of the sheet residual quantity.SOLUTION: A sheet feeder 2 has: a DC motor 9 which has characteristics that a driving amount decreases in accordance with increase in load; a feeding tray 6 which is vertically lifted by drive of the DC motor 9; and a feeding roller 3 which comes into contact with a sheet on the feeding tray to feed the sheet within a feeding possible range. The sheet feeder 2 further has: motor driving means 41 for intermittently driving the DC motor 9 for every predetermined time Tso as to repeat feeding by lifting the uppermost sheet which falls in accordance with feeding again according to an actuation start instruction after the uppermost sheet reaches a lower limit position; and residual quantity determination means 42 for determining the sheet residual quantity on the basis of the number of sheets fed from the top of the feeding tray between drives in predetermined time and the characteristics of the DC motor 9.

Description

  The present invention relates to a sheet feeding apparatus provided in an image forming apparatus such as a copying machine, a facsimile machine, a laser beam printer, and a multifunction machine, and an image forming apparatus provided with the sheet feeding apparatus.

  In the image forming apparatus, there is a technique for detecting the remaining amount of sheets stored for printing during printing. For example, in order to prevent the sheets from being lost during printing, a technique for detecting the remaining amount of sheets on the feeding tray and notifying the user that the remaining amount of sheets has become small has been proposed. This proposal can be used as a guide for replenishing the sheet, and the time during which the image forming apparatus is stopped because there is no sheet can be shortened. As a technique for detecting the remaining amount of the sheet, for example, the sheet remaining amount detection shielding plate that can be moved up and down together with the feeding tray and the remaining amount detection shielding plate that rises as the remaining amount of the sheet on the feeding tray decreases are shielded. If there is, there is one provided with a remaining amount detection sensor that outputs a detection signal (see Patent Document 1). In this configuration, the remaining amount of the sheet can be detected by the amount of the sheet decreasing and being detected by the remaining amount detection sensor.

  Further, the rear end guide plate and the front end aligning plate are arranged at the front end portion and the rear end portion of the sheet placement plate so as to be inclined in parallel with each other, and the front end position of the sheet on the sheet placement plate is determined. Some are configured differently. In this technique, when the remaining amount of the sheet is large, the leading edge position of the sheet to be sent out and the sheet arrival time to the sheet detection sensor arranged on the conveyance path become long. On the contrary, when the remaining amount of the sheet is small, the sheet arrival time to the sheet detection sensor is shortened. For this reason, the remaining amount of the sheet is determined based on the measurement of the time when the fed sheet reaches the sheet detection sensor (see Patent Document 2).

JP 11-292348 A JP 2008-37592 A

  However, in the image forming apparatus described in Patent Document 1, the remaining amount of the sheet, such as a remaining amount detection sensor, a mechanism that moves the remaining amount detection sensor along the guide, and a wiring that transmits a detection signal of the remaining amount detection sensor to the CPU. It was necessary to add a dedicated configuration for quantity determination. For this reason, there were problems in terms of cost and installation space.

  In the image forming apparatus described in Patent Document 2, a sheet detection sensor, a support mechanism that tilts the rear end guide plate and the front end alignment plate backward, and a wiring that transmits a detection signal of the sheet detection sensor to the CPU, etc. It was necessary to add a dedicated configuration for determining the remaining amount. For this reason, similarly to the above, there were problems in terms of cost and installation space.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a sheet feeding apparatus and an image forming apparatus having a configuration that is advantageous in terms of both cost and installation space by reducing the number of dedicated configurations specially added for determining the remaining amount of sheets as much as possible. And

  According to the present invention, in a sheet feeding apparatus, a driving source having a characteristic that a driving amount decreases with an increase in load, a sheet stacking unit that stacks sheets and moves up and down by driving of the driving source, and a sheet feeding A feeding means for feeding a sheet in contact with the sheet on the sheet stacking unit within a feedable range, and the uppermost sheet on the sheet stacking unit reaches a lower limit position of the feedable range After that, according to the received operation start command, the drive source is intermittently set for a certain period of time so that the uppermost sheet descending with the feeding on the sheet stacking unit is raised again and the feeding is repeated. Based on the driving means for driving, the number of sheets fed from the sheet stacking unit between the driving for a certain period of time and the driving, and the characteristics of the driving source, the remaining amount of sheets on the sheet stacking unit A remaining amount determining means for determining Characterized in that it obtain.

  According to the present invention, there is no need for a dedicated detection means for determining the remaining amount of sheets, and a dedicated configuration added specifically for determining the remaining amount of sheets is reduced, and a configuration that is advantageous in terms of cost and installation space is provided. Can be realized.

1 is a cross-sectional view illustrating a schematic configuration of an image forming apparatus including a sheet feeding device according to an embodiment of the present invention. (A) is a schematic perspective view of the sheet feeding apparatus in this embodiment, (b) is a schematic sectional view. FIG. 5 is a schematic characteristic diagram showing a correlation between a load torque and a rotation speed of a DC motor that drives the feeding tray in the embodiment to move up and down. FIG. 6 is a transition diagram of the position of the uppermost surface of a sheet bundle on a feeding tray in the present embodiment. The block diagram which shows the control system in this embodiment.

  Hereinafter, embodiments according to the present invention will be described in detail with reference to the drawings. FIG. 1 is a cross-sectional view illustrating a schematic configuration of an image forming apparatus 1 including a deck-type sheet feeding device which is an example of a sheet feeding device according to the present invention.

  As shown in FIG. 1, an image forming apparatus 1 that outputs an image by an electrophotographic method includes an image forming apparatus main body (hereinafter referred to as an apparatus main body) 30. The apparatus main body 30 includes a sheet feeding unit 24 at the center, and a so-called deck type sheet feeding apparatus 2 at the lower part. Each of the sheet feeding unit 24 and the sheet feeding device 2 is configured to be able to feed the sheets S one by one toward the image forming unit 23 as an image forming unit. Further, the image forming apparatus 1 includes a control unit 25 as a control unit that controls each unit of the image forming apparatus 1 including the sheet feeding device 2.

  The sheet feeding unit 24 includes a feeding roller 29 that feeds out the top sheet of the stacked sheet bundle (S) and a separation roller pair 27 that separates the sheet S fed by the feeding roller 29. doing.

  The apparatus main body 30 includes an image forming unit (image forming unit) 23 that forms an image on a sheet by an electrophotographic method. Under the control of the control unit 25, the sheet S is sent from the sheet feeding unit 24 or the sheet feeding device 2 to the image forming unit 23 to form an image.

  In the present embodiment, the control unit 25 is described as being provided for the entire image forming apparatus 1 including the sheet feeding device 2, but the present invention is not limited thereto, and the image forming unit 23 and the sheet feeding unit 24 are not limited thereto. And a control unit configured separately from the sheet feeding device 2.

  The image forming unit 23 includes a photosensitive drum 33 on which a toner image is formed, a laser scanner 38 that irradiates the photosensitive drum 33 with light corresponding to an image signal, and a transfer roller that transfers the toner image on the photosensitive drum 33 to a sheet. 34. A fixing unit 37 for fixing the toner image to the sheet is provided.

  When an image forming operation is started in the image forming unit 23 configured as described above, first, the laser scanner 38 irradiates light on the photosensitive drum 33 with light according to the image signal, so that an electrostatic latent image is formed on the photosensitive drum 33. An image is formed. Subsequently, the electrostatic latent image is developed with toner stored in the toner cartridge 28, whereby a toner image (visible image) is formed on the photosensitive drum 33.

  Further, when the sheet S is fed from the sheet feeding device 2 in parallel with such a toner image forming operation, the sheet S is transferred to the photosensitive drum 33 by the conveying roller pair 31 and the registration roller pair 22. The image is conveyed to the transfer unit 32 in synchronization with the formed image. The transfer unit 32 includes a photosensitive drum 33 and a transfer roller 34, and a toner image is transferred to the sheet S by applying a bias voltage to the transfer roller 34 in the transfer unit 32.

  The sheet S to which the toner image has been transferred in this way is then conveyed to the fixing unit 37 and is heated by the fixing unit 37 to fix the toner image, and then the apparatus main body via the discharge roller 36. 30 is discharged to the upper discharge unit 35.

  Next, the sheet feeding apparatus 2 in the present embodiment will be described in detail with reference to FIG. 2A is a schematic perspective view illustrating the configuration of the sheet feeding apparatus 2, and FIG. 2B is a schematic cross-sectional view including the sheet conveyance path.

  The sheet feeding device 2 includes a feeding tray 6 as a sheet stacking unit that moves up and down by driving a DC motor 9, a feeding roller 3 supported by an arm 47, and a separation roller pair 26 as a separating unit. , A conveying roller pair 20 as conveying means is provided. Furthermore, side regulating plates 8R and 8L, a rear end regulating plate 7 and the like are arranged in the storage unit 61 (see FIG. 2A for the side regulating plate 8L).

  The feeding roller 3 constitutes a feeding unit that feeds the sheet in contact with the sheet on the feeding tray 6 within a feedable range in which the sheet S can be fed. The DC motor 9 constitutes a drive source having a characteristic that the rotational speed nr (drive amount, see FIG. 3) for a predetermined time decreases as the load torque Tm (load) increases.

  The side regulating plates 8R and 8L regulate and hold the positions of both end portions of the sheet bundle S on the feeding tray 6. The rear end regulating plate 7 regulates and holds the position of the rear end portion of the sheet bundle S on the feeding tray 6. Further, the sheet feeding apparatus 2 has an open / close door 21 supported on the right side in FIG.

  The separation roller pair 26 includes a feed roller 5 and a retard roller 4 that separate the sheet S fed by the feeding roller 3. The conveyance roller pair 20 conveys the sheet S fed by the feeding roller 3 and separated and fed one by one by the separation roller pair 26 toward the apparatus main body 30. Reference numeral 39 denotes a guide portion that guides the sheet S that passes through the nip portion of the separation roller pair 26.

  As shown in FIGS. 2A and 2B, the feeding tray 6 serving as a sheet stacking unit that can stack and move the sheets S up and down is provided with a rear end regulating plate 7 that is long in the vertical direction. The front side of FIG. In this state, the feeding tray 6 is supported so that it can be moved up and down, and is moved up and down with respect to the side regulating plates 8R and 8L at both ends by the operation of the DC motor 9.

  The feeding roller 3 disposed above the feeding tray 6 is supported by one end of an arm 47 that is swingably supported by a frame (not shown) of the sheet feeding device 2 via an arm shaft 18. In this case, a feeding unit that feeds the sheet in contact with the uppermost sheet S1 on the feeding tray 6 is configured. The feeding roller 3 is disposed on the downstream side in the sheet feeding direction A, and a separation roller pair 26 as a separating unit including a feed roller 5 and a retard roller 4 is disposed further downstream thereof.

  At the four corners of the feeding tray 6 in plan view, wire fixing portions 6a are formed so as to protrude. One end of each of the wires 13a and 13b guided by the pulley 12 is fixed to each wire fixing portion 6a.

  On the upstream side in the sheet feeding direction A of the feeding tray 6, an elevating mechanism 19 that transmits the drive of the DC motor 9 as a driving source to the feeding tray 6 and moves up and down is disposed. The elevating mechanism 19 includes a winding pulley 11 that winds up the other ends of the wires 13a and 13b, a reduction large gear 16 as a reduction gear that rotates the winding pulley 11, and a reduction small gear that rotates the reduction large gear 16. 17. That is, the lifting mechanism 19 is disposed between the DC motor 9 and the feeding tray 6, and wires 13 a and 13 b that can pull the feeding tray 6, the winding pulley 11, and the driving of the DC motor 9 are driven by the winding pulley 11. Gears 16 and 17 for transmitting to the feed tray 6 and moving the feeding tray 6 up and down.

  A pulley shaft 48 extends in the left-right direction in FIG. 2A of the feeding tray 6, and the take-up pulley 11 is attached to both ends of the pulley shaft 48. The reduction large gear 16 is attached to the pulley shaft 48 together with the take-up pulley 11. Each pulley 12, the small reduction gear 17, and the DC motor 9 are supported by a frame (not shown) of the sheet feeding device 2.

  Further, a sensor shaft 14 a extending in the width direction orthogonal to the sheet feeding direction A is supported on a frame (not shown) of the sheet feeding apparatus 2. A sheet surface flag 14 is attached to the sensor shaft 14a on the front side in the width direction, and a light shielding member 14b is attached to a position facing the optical sensor 15 on the back side in the width direction. The sheet surface flag 14 rotates following the displacement of the uppermost sheet S1.

  The light shielding member 14b rotates integrally with the sheet surface flag 14 with the sensor shaft 14a as a fulcrum in order to keep the height of the uppermost sheet S1 on the feeding tray 6 constant, and the optical axis 15L of the optical sensor 15 Is switched between a light shielding state and a light projecting state. The sheet surface flag 14 and the optical sensor 15 constitute a sheet detecting unit that detects the uppermost surface of the sheet S placed on the feeding tray 6 as a sheet stacking unit.

  Next, a control system of the image forming apparatus 1 in the present embodiment will be described with reference to FIG. FIG. 5 is a block diagram showing a control system in the present embodiment.

  That is, as shown in FIG. 5, the control unit 25 as a control unit provided in the image forming apparatus 1 includes a motor drive unit 41, a remaining amount determination unit 42, and a roller drive unit 44. A door detection sensor 40, a sheet surface flag 14, an optical sensor 15, and an input unit 46 are connected to the input side of the control unit 25, and a DC motor 9, a notification unit 43, and a roller are connected to the output side. The drive part 45 is connected. The input unit 46 is provided in a predetermined part of the apparatus main body 30 and various kinds of print information and the like are input by a user or the like (not shown in FIG. 1).

The motor drive means 41 responds to the received printer start command (operation start command) after the uppermost sheet S1 on the feed tray 6 reaches the feed lower limit position (lower limit position of the feedable range) Hth. The drive means is configured to execute as follows. That is, the driving means intermittently drives the DC motor 9 for a predetermined time (a constant time) T L so that the uppermost sheet S1 descending with the feeding on the feeding tray is raised again and the feeding is repeated. Drive one by one. The motor driving means 41 drives the DC motor 9 by outputting a driving signal based on the detection of the sheet surface flag 14 as the sheet detecting means and the optical sensor 15. For example, after the sheet surface flag 14 and the optical sensor 15 detect the uppermost surface of the sheet, the DC motor 9 is driven for a predetermined time by outputting a drive signal.

The remaining amount determination means 42 is arranged on the feeding tray based on the number of sheets fed from the feeding tray 6 and the characteristics of the DC motor 9 between driving for a predetermined time (fixed time) TL. The remaining amount of sheet (on the sheet stacking unit) is determined. That is, the remaining amount determining means 42 is the number of sheets conveyed from the start of the driving of the DC motor 9 by the motor driving means 41 during the feeding of the sheet by the feeding roller 3 and a certain characteristic of the DC motor 9. The remaining amount of sheets on the feeding tray is determined by a predetermined calculation based on the above. The remaining amount determination unit 42 outputs a low remaining amount signal (remaining amount signal) when it is determined that the remaining amount of sheets on the feeding tray 6 has reached a predetermined number.

The remaining amount determining means 42 stores in advance characteristic data relating to the characteristic between the load torque and the rotational speed of the DC motor 9 to be used, and the following expression T m = (w p × Ns + W t ) × R d / Z d
m = (n × tm) / (2π × R d × Z d )
Is used to determine the remaining sheet capacity. Where w p is the weight of one sheet, Ns is the number of sheets on the feeding tray 6, W t is the weight of the feeding tray 6, R d is the radius of the take-up pulley 11, and Z d is decelerated from the DC motor 9. The reduction ratio up to the large gear 16, m is the rotational speed of the DC motor 9 for a predetermined time TL . Furthermore, n is the number of sheets fed from the feeding tray during the predetermined time TL driving, and tm is the thickness of one sheet.

  The notifying unit 43 as a notifying unit notifies that the remaining amount of sheets on the feeding tray 6 has decreased based on the low remaining amount signal output from the remaining amount determining unit 42. That is, the notification unit 43 indicates that the sheet on the feeding tray has reached the remaining amount set in advance by the user according to the low remaining amount signal output from the remaining amount determining unit 42 by sound, light, character display, or the like. Inform. As a result, the user can replenish the sheet and prepare for replenishment.

  The roller driving unit 44 rotationally drives the feeding roller 3, the feed roller 5, the retard roller 4, and the conveying roller pair 20 via the roller driving unit 45 according to the output of the signal. A roller driving unit 45 such as a motor rotates the feed roller 3, the feed roller 5, the retard roller 4, and the transport roller pair 20 in accordance with a signal output from the control unit 25.

  Next, a process in which the sheet S is supplied from the sheet feeding device 2 to the image forming apparatus 1 will be described with reference to FIGS. 1 and 2A and 2B.

  That is, when the user opens the door 21 to place the sheet bundle S on the feeding tray 6 and closes the door 21, the door detection sensor 40 (see FIG. 5) in the apparatus main body 30 closes the door 21. Detect. Based on this detection, the motor drive means 41 of the control unit 25 outputs a drive signal to drive the DC motor.

  Therefore, the rotation of the DC motor 9 is transmitted to the pulley shaft 48 via the small reduction gear 17 and the large reduction gear 16, and the take-up pulleys 11 at both ends of the pulley shaft 48 rotate together with the pulley shaft 48, whereby the wires 13a, 13 b is wound around the winding pulley 11. In accordance with the rotation of the take-up pulley 11, the feeding tray 6 is raised by lifting the wire fixing portions 6a at the four corners with the wires 13a and 13b.

Thereafter, when the uppermost sheet S1 comes into contact with the sheet surface flag 14, the uppermost sheet S1 reaches the feeding lower limit position Hth and the sheet surface flag 14 rotates about the sensor shaft 14a, the light shielding member 14b is moved to the optical sensor. 15 optical axes 15L are blocked. Then, since the optical sensor 15 transmits a detection signal corresponding to the change from the light projection state to the light shielding state (off to on) to the control unit 25, the motor driving unit 41 outputs the drive signal to the DC motor 9. Stop and stop its rotation.

  Next, when a printer start command (operation start command) by a user operation is transmitted to the control unit 25, the roller driving unit 45 rotates the feed roller 3, the feed roller 5, the retard roller 4, and the transport roller pair 20. Driven. As a result, the uppermost sheet S <b> 1 is sent out to the separation roller pair 26 by the rotation of the feeding roller 3.

  At this time, even if the uppermost sheet S1 is double-fed together with the sheet immediately below it, the uppermost sheet S1 is separated one by one by the nip between the feed roller 5 and the retard roller 4. Thereafter, the uppermost sheet S <b> 1 is conveyed to the conveyance roller pair 20 by the feed roller 5, and is conveyed to the image forming unit 23 via the conveyance roller pair 20.

Next, position control of the second and subsequent uppermost sheets S1 will be described. That is, the position of the uppermost sheet S1 is within the scope of the increase amount L F below, lower by the thickness of the sheet tm (see FIG. 4) by a single sheet conveyance. As the sheet surface position is lowered, the sheet surface flag 14 that contacts the uppermost sheet S1 rotates counterclockwise about the sensor shaft 14a in FIG.

The position of the uppermost sheet S1 is reached until the feed limit position H th in the range of increase amount L F, the optical axis 15L of the optical sensor 15 is released light shielding by the shielding member 14b, the optical sensor 15 From the light shielding state to the light projecting state (from on to off).

As a result, a detection signal associated with a change in the state of the optical sensor 15 from on to off is transmitted to the control unit 25, and the motor driving means 41 of the control unit 25 rotates the DC motor 9 by a predetermined time (a constant time) T L. To drive. For this reason, the feeding tray 6 is raised according to a certain characteristic between the acting load torque and the rotational speed (drive amount) for a predetermined time, which the DC motor 9 as the drive source has.

  By this control, the position of the uppermost sheet S1 changes as shown in FIGS. 4 (a) and 4 (b). In the case of a specific sheet type (paper type), FIG. 4A shows a case where the remaining sheet capacity is 300 sheets (when the sheet weight is heavy and the load torque from the feeding tray 6 to the DC motor 9 is large). Showing change. FIG. 4B shows a change when the remaining amount of sheets is 100 (when the sheet weight is light and the load torque from the feeding tray 6 to the DC motor 9 is small).

By repeating this control, the position of the uppermost sheet S1 is feeding and reaches the lower limit position H th, increase amount L F by increasing the amount of L F range is raised by the rotation drive of the predetermined time T L of the DC motor 9 It is returned to the topmost position and is kept at a position where it can be fed.

  Next, detection of the remaining amount of sheets on the feeding tray 6, which is a feature of the present invention, will be described. In general, as shown in the schematic graph of FIG. 3, the DC motor 9 in the present embodiment has a rotational speed within a predetermined time corresponding to a load torque that acts in a constant power supply state (a constant power supply state). Change. In FIG. 3, as the load torque Tm increases toward the maximum value Tmax, the rotational speed nr of the DC motor continues to decrease linearly from the maximum value no and changes to zero at the maximum value Tmax.

In the configuration of the present embodiment, the load torque with respect to the DC motor 9 varies according to the weight change corresponding to the remaining amount of sheets on the feeding tray 6. The characteristic of the DC motor 9, the rotation speed at a given time T L of the DC motor 9 (rotation amount, the drive amount) for changes, increase amount L F of the amount of increase in feeding tray 6 (FIG. 4 (a), the The amount of increase L L in FIG. 4B also varies. As described above, the above-described transition of the height of the uppermost sheet S <b> 1 due to the sheet conveyance changes corresponding to the change in weight due to the remaining amount of the sheet S on the feeding tray 6.

  For example, in the case of a specific sheet type (paper type), as shown schematically in FIGS. 4A and 4B, when the remaining amount of sheets S is 300 and 100, respectively, The height of the upper sheet S1 changes.

That is, when comparing FIG. 4 (b) 4 and (a), the conveying speed of the sheet from the driving start time T 1 of the DC motor 9 until the next drive start time T 2 is, sheet remaining amount compared with 300 sheets It can be seen that when the target is heavy, the remaining amount of the sheet is 100 sheets, which is two sheets less than when the sheet is relatively light.

That is, the characteristic of the DC motor 9, in view of the case sheet remaining amount of 300 sheets 4 (a), even in the drive in the same predetermined time T L, the increase amount L F when feeding tray 6 is heavy The amount of increase L L when light is smaller. Therefore, when the sheet is lowered by the same sheet thickness tm by the feeding and reaches the feeding lower limit position Hth , a portion (sheet thickness) that falls in a stepped manner as compared with FIG. There are two places where tm falls stepwise.

In other words, when the remaining amount of sheets on the sheet tray 6 is gradually progressively decreased from 300 sheets, the number of which is fed between the drive starting time T 1 until the next drive start time T 2 are, relatively light In the state where there are 100 sheets, there are about 2 sheets more than 5 sheets at 300 sheets. A method for determining the remaining amount of sheet using the difference in the number of sheets conveyed (number of feeding) will be described in detail below.

  That is, the remaining amount determination unit 42 of the control unit 25 outputs sheets from the rotation command (operation start command) of the DC motor 9 in the second and subsequent sheets of the print job output from the motor driving unit 41 to the next rotation command. Count the number of conveyances. This sheet conveyance number (feed number) is n. As described above, the sheet conveyance number n varies in conjunction with the characteristic table shown in FIG. 3 in accordance with the load torque acting on the DC motor 9.

The load torque T m applied to the DC motor 9 is reduced from the weight W s of the sheet bundle S on the feeding tray 6, the weight W t of the feeding tray 6, the radius R d of the take-up pulley 11, and the DC motor 9. with reduction ratio Z d to the large gear 16, represented by the following formula (1).
T m = (W s + W t ) × R d / Z d (1)

The weight W s of the sheet bundle S is expressed by the following expression (2) using the weight w p of one sheet and the number Ns of sheets included in the sheet bundle S.
W s = w p × Ns (2)

Then, when Expression (2) is substituted into Expression (1), the following Expression (3) is obtained.
T m = (w p × Ns + W t) × R d / Z d ... (3)

Further, the amount of increase L of the feed tray 6 from the drive start time T (T 1 , T 2 ...) To the predetermined time TL is the number of rotations m of the DC motor 9 during the predetermined time TL , Using the radius R d and the reduction ratio Z d from the DC motor 9 to the reduction large gear 16, it is expressed by the following equation (4).
L = 2π × R d × m × Z d (4)

Further, the amount of increase L (L F , L L ) of the feeding tray 6 for a predetermined time T L is the number n of sheet conveyances from the rotation command of the DC motor 9 to the next rotation command and the thickness of one sheet. Using tm, it can be approximated by the following equation (5).
L≈n × tm (5)

Then, by substituting Equation (5) into Equation (4) for L and transforming it, the following Equation (6) can be obtained. That is, the rotational speed m of the DC motor 9 for a predetermined time TL can be obtained by the following equation (6).
m = (n × tm) / (2π × R d × Z d ) (6)

  The remaining amount determination means 42 of the control unit 25 stores data of the torque characteristic diagram of the DC motor 9 shown in FIG. 3, and the sheet conveyance from the rotation command of the DC motor 9 to the next rotation command is performed during printing. Store the number n. For this reason, Expressions (3) and (6) are calculated using the torque characteristic diagram of the DC motor 9 to calculate the number Ns of sheets included in the sheet bundle S, that is, the remaining sheet amount on the feeding tray 6. Can be obtained at

However, the weight W t of the feeding tray 6, the radius R d of the take-up pulley 11, and the reduction ratio Z d from the DC motor 9 to the reduction large gear 16 are constants determined when the sheet feeding apparatus 2 is designed. On the other hand, the weight w p and the thickness tm of one sheet in the equations (3) and (6) are variables depending on the sheet type (paper type) used by the user.

As for the weight w p and the thickness tm of one sheet, values input by the user from the input unit 46 of the image forming apparatus 1 are used. Alternatively, a size detection sensor that detects the sheet size and a media sensor that can detect the basis weight and thickness of the sheet are provided in the apparatus main body 30, and one sheet is obtained based on the detection result obtained by these sensors. it may be configured to calculate the weight w p and thickness tm.

  The control unit 25 displays the number Ns of sheets included in the sheet bundle S obtained by the remaining amount determination unit 42 in the above calculation using the user operation panel as the notification unit 43 attached to the apparatus main body 30 to the user. It can be reported as a quantity. Alternatively, it is also possible to notify the user of the remaining sheet capacity by displaying a display of a personal computer (PC) mounted on the apparatus main body 30 via a network as the notification unit 43.

Further, since the number of sheets Ns sheet remaining on the feed tray 6 it is included in the less becomes the sheet bundle S is reduced, the equation (3), for short seat weight w p and the number of sheets Ns following formula (7) Can be approximated as follows.
T m ≈W t × R d / Z d (7)

Even when the value of the weight w p of one sheet is unknown, when the data of the sheet thickness tm is input to the control unit 25, the remaining amount determination means 42 uses the expressions (6) and (7). Thus, it is possible to accurately determine that the remaining amount of sheets on the feeding tray is small and notify the user of this.

  As described above, as described in the present embodiment, by using the characteristics of the load torque of the DC motor 9 and the rotation speed for a predetermined time, it is possible to use a dedicated detection unit and a sheet arrangement unit that requires space. The remaining amount of sheets on the feeding tray 6 can be detected. As a result, it is possible to provide the sheet feeding device 2 and the image forming apparatus 1 having a configuration advantageous in terms of cost and installation space while reducing the number of dedicated configurations that are specially added for determining the remaining amount of sheets.

DESCRIPTION OF SYMBOLS 1 ... Image forming apparatus, 2 ... Sheet feeding apparatus, 3 ... Feeding means (feeding roller), 6 ... Sheet stacking part (feeding tray), 9 ... Drive source (DC motor), 11 ... Winding pulley, 13a, 13b ... wire, 16 ... reduction gear (deceleration large gear), 19 ... elevating mechanism, 23 ... image forming means (image forming section), 41 ... driving means (motor driving means), 42 ... remaining amount determining means, H th ... lower limit position of feedable range (feed lower limit position), m ... number of rotations of DC motor for a fixed time, Ns ... number of sheets on sheet stacking portion (number of sheets on feed tray), n ... fixed time R d ... radius of take-up pulley, S ... sheet, S1 ... sheet (uppermost sheet), T L ... fixed time (predetermined time), tm ... of one sheet Thickness, W t ... weight of sheet stacking portion (weight of feeding tray), w p ... Weight of one sheet, Z d ... Reduction ratio from DC motor to reduction gear (deceleration large gear)

Claims (6)

  1. A drive source having a characteristic that the drive amount decreases as the load increases;
    A sheet stacking unit that stacks sheets and moves up and down by driving the drive source;
    A feeding means for feeding the sheet in contact with the sheet on the sheet stacking unit within a feedable range in which the sheet can be fed; and
    After the uppermost sheet on the sheet stacking unit reaches the lower limit position of the feedable range, the uppermost sheet that descends with the feeding on the sheet stacking unit is returned again according to the received operation start command. Driving means for driving the driving source intermittently at a fixed time so as to repeat the feeding by raising;
    Remaining amount determination for determining the remaining amount of sheets on the sheet stacking unit based on the number of sheets fed from the sheet stacking unit and the characteristics of the driving source between driving for a certain time Means,
    A sheet feeding apparatus characterized by that.
  2. The drive source is a DC motor having the characteristic that the rotational speed that is the drive amount decreases as the load torque that is the load increases.
    A wire disposed between the DC motor and the sheet stacking unit and capable of pulling the sheet stacking unit, a winding pulley for winding the wire, and a reduction gear for transmitting the drive of the DC motor to the winding pulley And a lifting mechanism that lifts and lowers the sheet stacking unit by driving the DC motor.
    The sheet feeding apparatus according to claim 1, wherein
  3. The remaining amount determining means includes
    Characteristic data relating to the characteristic between the load torque and the rotation speed of the DC motor to be used is stored in advance, and the following equation T m = (w p × Ns + W t ) × R d / Z d
    m = (n × tm) / (2π × R d × Z d )
    To determine the remaining sheet amount,
    (However, w p is the single sheet weight, Ns is the number of sheets on the sheet stacking portion, the weight of W t is the sheet stacking portion, R d is the radius of the winding pulley, the Z d from the DC motor Reduction ratio to the reduction gear, m is the number of revolutions of the DC motor for a certain period of time, n is the number of sheets fed from the sheet stacking section during the certain period of driving, and tm is one sheet Thickness)
    The sheet feeding apparatus according to claim 2, wherein the sheet feeding apparatus is a sheet feeding apparatus.
  4. The remaining amount determining means outputs a remaining amount signal when it is determined that the remaining amount of sheets on the sheet stacking unit has reached a predetermined number;
    The sheet feeding apparatus according to claim 1, wherein the sheet feeding apparatus is a sheet feeding apparatus.
  5. Based on the remaining amount signal output from the remaining amount determining unit, a notification unit that notifies that the remaining amount of sheets on the sheet stacking unit has decreased,
    The sheet feeding apparatus according to claim 4, wherein the sheet feeding apparatus is a sheet feeding apparatus.
  6. A sheet feeding device according to any one of claims 1 to 5,
    Image forming means for forming an image on a sheet fed from the sheet feeding device;
    An image forming apparatus comprising:
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Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH01231735A (en) * 1988-03-09 1989-09-18 Sharp Corp Residual quantity of paper detector for lift type paper feed cassette
JPH06191676A (en) * 1992-02-19 1994-07-12 Fujitsu Ltd Residual sheet detecting device
JPH10181944A (en) * 1996-12-25 1998-07-07 Fuji Xerox Co Ltd Paper residual quantity detecting method of image former
JP2000255797A (en) * 1999-03-08 2000-09-19 Fuji Xerox Co Ltd Recording material feeder and image forming device
JP2007008626A (en) * 2005-06-29 2007-01-18 Konica Minolta Business Technologies Inc Image forming device
JP2010100426A (en) * 2008-10-27 2010-05-06 Fuji Xerox Co Ltd Sheet residual quantity detection device and image forming device
JP2012246134A (en) * 2011-05-31 2012-12-13 Kyocera Document Solutions Inc Paper remaining amount detection device, and image forming apparatus

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH01231735A (en) * 1988-03-09 1989-09-18 Sharp Corp Residual quantity of paper detector for lift type paper feed cassette
JPH06191676A (en) * 1992-02-19 1994-07-12 Fujitsu Ltd Residual sheet detecting device
JPH10181944A (en) * 1996-12-25 1998-07-07 Fuji Xerox Co Ltd Paper residual quantity detecting method of image former
JP2000255797A (en) * 1999-03-08 2000-09-19 Fuji Xerox Co Ltd Recording material feeder and image forming device
JP2007008626A (en) * 2005-06-29 2007-01-18 Konica Minolta Business Technologies Inc Image forming device
JP2010100426A (en) * 2008-10-27 2010-05-06 Fuji Xerox Co Ltd Sheet residual quantity detection device and image forming device
JP2012246134A (en) * 2011-05-31 2012-12-13 Kyocera Document Solutions Inc Paper remaining amount detection device, and image forming apparatus

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